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How can I figure out the right value for the DISPLAY variable?

Hi,

Here is my Linux version ...

Code:

Linux qa1234c 2.6.18-194.8.1.el5 #1 SMP Wed Jun 23 10:52:51 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux

We are trying to run some google web toolkit integration tests, but the ones that rely on a display die with the error ...

Code:

Caused by: java.lang.Exception: java.lang.InternalError: Can't connect to X11 window server using 'localhost:10.0' as the value of the DISPLAY variable.

        at sun.awt.X11GraphicsEnvironment.initDisplay(Native Method)

        at sun.awt.X11GraphicsEnvironment.access$100(X11GraphicsEnvironment.java:52)

        at sun.awt.X11GraphicsEnvironment$1.run(X11GraphicsEnvironment.java:155)

        at java.security.AccessController.doPrivileged(Native Method)

        at sun.awt.X11GraphicsEnvironment.<clinit>(X11GraphicsEnvironment.java:131)

        at java.lang.Class.forName0(Native Method)

        at java.lang.Class.forName(Class.java:169)

        at java.awt.GraphicsEnvironment.getLocalGraphicsEnvironment(GraphicsEnvironment.java:68)

        at java.awt.image.BufferedImage.createGraphics(BufferedImage.java:1135)

        at com.google.gwt.resources.rg.ImageBundleBuilder.toPng(ImageBundleBuilder.java:538)

        at com.google.gwt.resources.rg.ImageResourceGenerator.reencodeToTempFile(ImageResourceGenerator.java:641)

        at com.google.gwt.resources.rg.ImageResourceGenerator.prepare(ImageResourceGenerator.java:567)

        at com.google.gwt.resources.rebind.context.AbstractClientBundleGenerator.initAndPrepare(AbstractClientBundleGenerator.java:1043)

        at com.google.gwt.resources.rebind.context.AbstractClientBundleGenerator.initAndPrepare(AbstractClientBundleGenerator.java:1069)

        at com.google.gwt.resources.rebind.context.AbstractClientBundleGenerator.generateIncrementally(AbstractClientBundleGenerator.java:412)

        at com.google.gwt.dev.javac.StandardGeneratorContext.runGeneratorIncrementally(StandardGeneratorContext.java:647)

        at com.google.gwt.dev.cfg.RuleGenerateWith.realize(RuleGenerateWith.java:41)

        at com.google.gwt.dev.shell.StandardRebindOracle$Rebinder.rebind(StandardRebindOracle.java:78)

        at com.google.gwt.dev.shell.StandardRebindOracle.rebind(StandardRebindOracle.java:268)

        at com.google.gwt.dev.shell.ShellModuleSpaceHost.rebind(ShellModuleSpaceHost.java:141)

        at com.google.gwt.dev.shell.ModuleSpace.rebind(ModuleSpace.java:585)

        at com.google.gwt.dev.shell.ModuleSpace.rebindAndCreate(ModuleSpace.java:455)

        at com.google.gwt.dev.shell.GWTBridgeImpl.create(GWTBridgeImpl.java:49)

        ... 43 more

I have tried setting my DISPLAY variable to ":0", ":10.0", and "localhost:10.0" but all failed. I have Xvfb installed. How can I figure out the proper values for the DISPLAY variable, or at least a strategy for attacking this error? Thanks - Dave

try typing:

Code:

xhost +

This should allow - DISPLAY variable to work - I'd set DISPLAY=10.0

What xhost+ does is it grants access to everyone trying to access X server. If you want to limit it to localhost do a:

Code:

xhost + localhost

I tried this on a command line, but didn't get very far ...

Code:

ccqavob02c:/home/e18538 $ export DISPLAY=10.0

ccqavob02c:/home/e18538 $ xhost +

xhost:  unable to open display "10.0"

Further thoughts? - Dave

Most times, DISPLAY is

Code:

:0.0

Code:

localhost:0.0

As kbscores mentioned, you need to allow the connection via xhost.
There are different versions for the syntax. On my system, it is

Code:

xhost +

for ALL or

Code:

xhost +local:

for local clients.

For all of these versions, you need the x server to be up and running. I'm not sure if xvfb is sufficient.

Why "10.0"? The current one is usually ":0.0". Maybe ":10.0"? It's still weird, though.
Maybe you should check the google web toolkit docs and try to figure this out.
Maybe you need to open a xnest or a xephyr on DISPLAY :10.0 .

I think I'm missing what "xhost" is supposed to do. My question is how do I figure out what the valid values of DISPLAY should be? I'm still getting these errors ...

Code:

[e18538@qa3398c ~]$ export DISPLAY="localhost:0.0"

[e18538@qa3398c ~]$ xhost +

xhost:  unable to open display "localhost:0.0"

[e18538@qa3398c ~]$ xhost +local

xhost:  unable to open display "localhost:0.0"

or if using DISPLAY=:0.0 ...

Code:

[e18538@qa3398c ~]$ export DISPLAY=":0.0"

[e18538@qa3398c ~]$ xhost +

xhost:  unable to open display ":0.0"

[e18538@qa3398c ~]$ xhost +local

xhost:  unable to open display ":0.0"

Thanks - Dave

It most likely depends on where you want to display. For instance -- you have a server and a client --

On server use:

Code:

xhost +

On client:

Code:

export DISPLAY=ServerIP:0.0

./xprogram

The above code will run xprogram from client on display 1 of server.

So Same concept for doing this locally - Instead of there being two machines just do both steps on a single machine.

Code:

xhost + 

export DISPLAY=localhost:0.0

./xprogram

Also - Lets say you were using a sunray - which typically has several Displays - echo $DISPLAY of terminal to diplay xprogram and instead of 0.0 you would want to use whatever echo $DISPLAY output.